I-Y33765 and ancient DNA - Spiginas 1

Most of what we know about the I-Y33765 clade is based on interpretation of results from Y-DNA samples taken from ten men. Four of these men live in England, and another four in Sweden.  The two remaining DNA donors both have family origins in England but their nineteenth century ancestors migrated either to the United States or to New Zealand.  An obvious, but very important, characteristic of all these men is that, when their DNA samples were collected they were all living.  In other words their Y-DNA is modern.  

In previous articles I have used results of their Y-DNA analysis and details of their documented genealogies to speculate on the geographic origins of the I-Y33765 clade.  In particular, I have used the genealogies of the four modern Swedish men to support a narrative in which I have linked the Viking age patriarch of our clade to the south eastern part of present-day Sweden and more specifically to the area of Tjust.  While it seems to me such speculation is helpful and productive it's credibility rests on the unproven assumption that the places of residence of the ancestors of modern Swedish Y-DNA donors during the seventeenth century will be approximately localised in the area inhabited, 1000 years earlier, by their shared Viking age patriarch.  Without some additional evidence that seems a large leap of faith.

Obviously, it would be very nice to have an ancient DNA sample from Sweden that is derived for Y33765, but the expense and difficulties of finding, extracting and sequencing ancient DNA make the existence of such optimal evidence rather improbable.  At present only two ancient DNA samples with Y-DNA identified as haplogroup I-L233 or one of it's downstream clades have been published; "Spiginas 1", an I-L233 late mesolithic adult male excavated in Lithuania in 1985 and "5860-13" (also known as VK22) an I-A8462 12th century adult male excavated in north-western Russia in 1938-40.  At first glance, a feature common to these specimens, and especially interesting in the context of the apparent modern locus of I-Y33765 in Sweden, is that both were found in regions that border the Baltic Sea. 

Figure 1: Geographic and phylogenetic relationship between Spiginas1, 5680-13 (VK22) and I-Y33765  

In this and the next article I intend to examine the published archaeology of both these I-L233+ men and see how this may help us test our present hypothesis that I-Y33765 originated in south-eastern Sweden.  

First, it seems appropriate to consider the older ancient DNA sample Spiginas 1.  This is the designation given to a 6000y old Mesolithic or Sub-Neolithic I-L233+ male hunter-gatherer excavated from a small cemetery in Western Lithuania in 1985-86.  His grave was closely grouped with three others (Spiginas 2, 3 & 4) on the former island of Spiginas in the marshy southern part of Lake Birzulis.  In the southeastern Baltic region there are no large stone-age burial sites and human remains are instead found singly or in small cemeteries, as at Spiginas and another island cemetery in Lake Birzulis, Duonkalnis, where 14 graves were excavated in 1985.  At Spiginas the four burials were on the summit of a glacial kame formation at an elevation of 163m above sea level and their radiocarbon date estimates span more than 4000 years (7780ybp, Kunda culture, Spiginas 4 to 3580ybp, Neolithic corded ware culture, Spiginas 2).  Two papers (Butrimas, 1992; Balcione, Cesnys & Jankauskas, 1992) describing the original archaeological investigations are written in Lithuanian and each has an English and Russian summary.

Figure 2: Mesolithic sites in the area of Birzulis Lake (from original paper by Butrimas,1992).

1, the sites of Swiderian culture; 2, early Mesolithic sites of Pulli type of the Kunda culture; 3, sites of the Middle and the Late Mesolithic; 4, sites of the early Mesolithic sites of Pulli type and of the Late Mesolithic; 5, sites of undetermined chronological determination; 6, Mesolithic graves; 7. Stray find location of bone point of Kunda type.  Sites: 1. Kulnikas   2. mesolithic graves of Spiginas island   3. Spigino sala   4. Spigino Ragas   5. Oznagaris1   6. Oznagaris2   7. Oznagaris3   8. Birzulio Sasmauka   9. Birzulio Sasmauka2   10. Dreniai   11. Lingenai   12. Duonkalnis   13.

According to the excavation report English abstract (Butrimas, 1992) the grave of Spiginas 1 "was destroyed during World War II, and only fragments of long bones and a skull have preserved. Two flint arrow heads of early Kungemosen microlith type were found among these bone fragments".  Translation of the Lithuanian text of Butrimas, 1992, dealing with the Spiginas 1 grave confirm that as a result of the war-time disturbance "fragments from this grave were dispersed over a fairly large area - 4 x 4m, but mainly within the presumed grave site. Blurred contours of the grave pit is exposed at a depth of 45-48cm.  In the pit two romboid flint (cross) arrowheads [see Figure 4]. At the north-east boundary of the grave was a small pebble covered in brownish ochre. Three more small ochre patches were observed in various areas of the grave [see Figure 3]. North of the grave there was a recent shell hole and disturbed ground.  Material from the grave pit was given to the Moscow Institute of Geological and Geochemistry Isotope Geochronology Laboratory (USSR).  The grave dated from 5020 +/ -200 ybp, 3070 +/- 200BC.  This radiocarbon date suggests that the grave is early Neolithic.  However, arrowheads and grave No4 date suggests this date underestimates the true age. Anthropologists believe that a 35-45y old man is buried."

Figure 3: Spiginas 1 grave situation plan (from original paper by Butrimas,1992). 1 - bone fragments  2 - flint  3 - ochre covered pebble  4 - ochre  5- disturbed ground  6 -  grave outline  (after Figure 3 from Butrimas, 1992.  Although no scale is specified in the original paper it seems possible that the plan represents the 4 metre by 4 metre area over which “fragments from this grave were dispersed”)

Figure 4: The two early Kungemosen microlith type rhomboid flint arrowheads from Spiginas 1 grave pit (Figure 5 from Butrimas, 1992).  These appear to have been “grave goods” but could possibly be the cause of injury or death of Spiginas 1?  The only source of flint in the Eastern Baltic is in Estonia and this is very poor in quality (Tringham, 1971, page 60)

Figure 5: Drawings of the two flint points from the Spiginas 1 grave pit. (Figure 10 from Ostrauskas, 1996)

The second original paper (Balcioniene, Cesnys & Jankauskas, 1992) gives more detail on the skeletal remains of Spiginas 1.  From the English summary,“In Grave 1 a male,35-45 years old, was buried.  Craniometric analysis was impossible; teeth were abrased to the 3^rd – 4^th degree.  M¹  had four tubereles and was quite massive.  Oesteometrical data are presented in Tabes 3 – 7.  No pathological changes were identified”.  Transaltion of the Lithuanian text indicates that “of the skeleton there remained a left maxillery fragment, right radial shaft, the right ulna, without the distal end of the femoral shaft, the distal end of the left tibia shaft, right and left fragment of the fifth metatarsal. …… tooth wear is consistent with a 35-45 year old".

Mittnik, A et al. (2018) use Spiginas 1 as one of ten samples representative of the Narva culture that occupied the eastern Baltic region from the late Mesolithic to the Middle Neolithic (Baltic EMN Narva).  They report his Y chromosomal haplogroup is I which they further refine to I2a1a2a1a based on L233:G→A (2x) (see their Supplementary Information, Supplementary Note 3. They also report he has one upstream mutation for haplogroup I2a1a2a (L1286: G→A at 1x) and one mutation for I2a1 (PF4004: T→C at 1x) and I2a (L460: A→C at 1x).  In addition they determined his mitochondrial DNA haplogroup was H11a (see their Table 1) and they note that while this haplogroup is “normally associated with the Neolithic expansion into Europe, but (he) shows no evidence of Neolithic farmer ancestry on the nuclear level suggesting that this haplogroup might have been present already in foraging groups”.  The woman who founded the H11a mitrochondrial haplogroup lived between 8000 and 4200 ybp (Behar et al., 2012).

Figure 6: Frequencies of four selected Y haplogroups in ancient DNA samples from Europe (from original paper by Jobling & Tyler-Smith, 2017).  The dark blue line shows the decline in haplogroup I2 from its significant proportion of the male population during the Mesolithic to a possible nadir approximating to the late Bronze age.

So, based on radiocarbon dating and the flint grave goods we can infer that Spiginas 1 lived in a late Mesolithic or early Neolithic hunter-gatherer society centered on Lake Birzulis.  Butrimas (2017) has speculated on the basis of archaeological, linguistic and historical evidence that the northern part of this lake represents a ritual complex of cemeteries, sacrificial hearths and funerary feast sites which date from the middle Mesolithic period to historical times.  He considers the four graves at Spiginas to be part of this ritualistic landscape.

At the time Spiginas 1 was buried at lake Birzulis the I2 Y-DNA haplogroup constituted a significant proportion of the European male population (see Figure 6).  The decline in haplogroup I2 from about 3000BC has been linked with the migration of populations from the Eurasian steppe which introduced significant cultural and genetic replacement, including R haplogroup Y-DNA (principally R1b) into central and western Europe and eventually the British Isles (Olalde et al., 2018).  In Scandinavia these migrations are characterized by the Corded Ware Culture (CWC) (also termed Battle-Axe Culture within Scandinavia) which in this region notably introduced R1a Y-DNA (Mittnik et al., 2018; Gunther et al., 2018) 

However, for the ancestral narrative of our I-Y33765 clade in SE Sweden, the significant neolithic culture is associated with the indigenous Scandinavian Hunter Gatherers (SHG).  These SHG peoples are derived from a mixture of Western (WHG) and Eastern Hunter Gatherer (EHG) populations (Gunther et al., 2018) in which the dominant male haplogroups are G and I2.  The Narva culture, of which Spiginas 1 is a member are genetically closer to WHG than EHG and hence Spiginas 1 can be considered genetically related to SHG men.

Within south eastern Sweden, Denmark and Estonia CWC sites are more usually associated with inland locations and with herding and farming while the SHG sites are typically coastal and involve a mobile maritime lifestyle that is called the Pitted Ware Culture (PWC).  The nomenclature "corded" or "pitted" refers to decorative characteristics of the pottery produced by the respective cultural groups.  The principle food source for PWC populations were seals and fish, giving them a nickname as "Inuit of the Baltic".  A recent study (Coutinho et al., 2020) of twelve male skeletons from three PWC sites on the island of Gotland was able to characterize the Y-DNA for eight of the individuals and each belonged to haplogroup I2.  Fifty percent of the total sample (n=6) were confirmed as haplogroup I2a (I-CTS595).  The radiocarbon dates for these individuals are estimated within the range 3000-2500 yBCE and so are not dissimilar to that quoted for Spiginas 1.  Also like the Spiginas grave PWC burial rituals involve single individual graves and include the use of red ochre.

Gotland is about 100km from the Swedish mainland but slate arrow points, found in some PWC graves on the island, seem to substantiate contact with mainland sources to obtain this material.  During the past century PWC sites have been recorded at many coastal locations bordering the Baltic (see Figure 7).  In Tjust, Smaland, Sweden, (see Figure 8) PWC sites have been excavated, at Hellero and Gardsholmens, north of Vastervik.  Finds from Vivastemala, which is just to the south of Vastervik have been important in interpreting Pitted Ware pottery in south-east Sweden because the styles found there in the late 1930's were very similar to those found at PWC sites in east central Sweden (Papmehl-Dufay, 2006).  Clearly, because of their maritime lifestyle, PWC populations would have appreciated the opportunities offered by the Tjust archipelago.   

Figure 7: Pitted Ware Culture (PWC) sites in Southern Scandinavia (after Douglas Price, 2015)

After about 2800yBCE there is archeological evidence for cultural contacts between CWC and PWC so that from about 2400yBCE, the PWC becomes absorbed into the late CWC or Battle Axe Culture (BAC). Further sources have suggested that the resulting Nordic Bronze Age population was the progenitor for the Germanic tribes which dispersed throughout Europe during the Migration Period.  

 

Figure 8: Pitted Ware sites in the Tjust archipelago

In summary, the Spiginas 1 individual is a representative of hunter-gatherer societies of the Baltic region.  His genomic DNA seems closer to WHG rather than EHG populations and his I2 Y-DNA haplogroup is found at high frequencies in pre-Neolithic samples from Europe but becomes progressively less common from the early Neolithic onward.  The coastline of south east Sweden was home to the last humans to adopt a hunter-gather lifestyle in Europe, the PWC, who had a mobile maritime lifestyle.  Genetic analysis of male PWC graves on Gotland shows a high frequency of the I2a Y-DNA haplogroup throughout the Neolithic. Several PWC sites have been excavated in the Tjust archipelago. 

References

Balcioniene, I.,Cesnys, G & Jankauskas, R.,(1992) Craniometry, Odontology, Osteometry and Paleopathology of the Mesolithic graves from Spiginas, Lietuvas Archeologia, v8,  p10-16

Behar, D.M. et al (2012) A “Copernican” reassessment of the human mitochondrial DNA tree from its root.  American J of Human Genetics, 90(4), 675-684

Butrimas, A (1992) Mesolithic Graves from Spiginas, Lietuvos Archeologia, v8,  p4-9

Butrimas, A (2017) From Mesolithic to Early Christianity: The development of the ritual Complex in the northern part of Lake Birzulis (Lithuania) according to archaeological, linguistic and historical research. Sociology and Anthropology, 5, 204-219

Cesnys, G.,Butrimas, A., (2009) Reinventing Mesolithic skulls in Lithuania: Donkalis and Spiginas sites.  Acta Medica Lituanica, 16, 1-8

Coutinho, A.,Gunther,T.,Munters,A.R.,Svensson,E.M.,Gotherstrom,A.,Stora,J.,Mailmstrom,H., & Jakobsson, M. (2020) The Neolithic Pitted Ware culture foragers were culturally but not genetically influenced by the Battle Axe culture herders. American Journal of Physical Anthropology, 172, 638-649

Douglas Price, T (2015) Ancient Scandinavia, OUP, Oxford, 494pp

Gunther, T et al. (2018) Population genomics of Mesolithic Scandinavia: Investigating early post-glacial migration routes and high-latitude adaption.  PLOS Biology, 16, e2003703, https://doi.org/10.1371/journal.pbio.2003703

Jobling, M.A & Tyler Smith, C (2017) Human Y-chromosome variation in the genome sequencing era. Nature Reviews Genetics, 18, 485-497

Mittnik, A et al. (2018) The Genetic Prehistory of the Baltic Sea region, Nature Communications

Ostrauskas, T. (1996) The Mesolithic in Western Lithuania, Lietuvos Archeologia, v14,  p192-212

Papmehl-Dufay, L. (2006) Shaping an Identity. Pitted Ware pottery and potters in southeast Sweden. Theses and Papers in Scientific Archaeology 7, Stockholm University, Sweden, 329pp

Trinham, R.(1971) Hunters, Fishers and Farmers of Eastern Europe 6000-3000 BC, Hutchinson University Library, Hutchinson & Co, London

 

I-Y33765 and other Baltic Sea branches of I-Y4252

As at January 2022 FTDNA's Block Tree contained twenty branches immediately downstream of I-Y4252.  Similarly the YFull Tree v.9.05 contains sixteen clades at this position.  Bernie Cullen has written (2020) that "I-Y4252 had a rapid "star-like" expansion" and the number of "rays" emanating from this particular star have increased steadily since the discovery of I-Y4252 in 2014.  This trend will very likely continue as the number of Y4252 (+) men who have Next Generation Sequencing (NGS) results increase.  

It seems to me this burst of branching must indicate a period of enhanced reproductive success for the early group of I-Y4252 men.  Based on NGS results YFull date this phylogenetic expansion to about 2000ybp and it is worth noting that this makes it approximately concurrent with the geographical expansion of Germanic tribes in northern Europe which itself was triggered by social pressures and technological changes that developed within their society about this time. The modern incidence of I-Y4252 which is illustrated by the Phylogeographer Y Heatmap (Figure 1) shows that haplogroup is today distributed throughout the British Isles and across north-west Europe and southern Sweden, with two outliers centred on Dalmatia in the south and Lapland in northern Finland.  Again, this extended geographic spread within such a recent haplogroup suggests to me that the original ancestral cohort were able to migrate easily and that their descendants were comparatively successful within the environments they colonized.

 

Figure 1: Modern incidence of I-Y4252 in Europe (source:https://phylogeographer.com/scripts/heatmap.php ) 

Seven of these I-Y4252 clades contain samples with putative ancestral origins in areas that surround the Baltic Sea and in each case the branch has also recorded positive results from England (Table 1 and Figure 2).  

Table 1: Baltic Clades downstream of I-Y4252 as at January, 2022.  The "SNP" column shows the date at which the SNP that defines the clade was discovered.  The "Baltic Sample" column shows the YFull ID of men whose earliest documented direct-male ancestor lived near the Baltic Sea and the NGS test they have used.

In defining these Baltic clades I have included those branches which contain a sample with an ancestral location that is approximately within a distance of 200km (125 miles) of the shoreline of the Baltic Sea and also that contains a sample whose ancestral location is within England. I have used this methodology because it seems to me these several examples of geographically discrete, shared Y-DNA, support the idea of historical contacts between the Baltic Sea region and England.  

 

Figure 2: Distribution of the earliest known locations for the seven Baltic clades within I-Y4252

The areas bordering the Baltic Sea where I-Y4252 clades have been identified are extensive.  They stretch from north-western Germany and West Pomerania in the south, to Lapland on the shores of the Gulf of Bothnia in the north and from Denmark and southern Sweden in the west to north of St Petersburg at the eastern extremity of the Gulf of Finland.  It also seems to me that such an extensive distribution must reflect the importance of the sophisticated maritime culture that established long-distance trading contacts throughout the Baltic region during the Scandinavian bronze and early iron ages.

Each of these clades has a TMRCA during the first millennium (160 AD to 870AD) and so it would seem reasonable to conclude that their geographic distribution may be an echo of the contacts between England and the various parts of Scandinavia that occurred during the Dark Ages.   An exception to this is the I-FGC56815 branch (see Table 1) in which the clade that contains a supposed Baltic sample, I-FGC56855 (I-Y131221), has a significantly later TMRCA during the sixteenth century and consequently would seem to represent much later interactions.  

Poznik et al. (2016) have demonstrated that "at times of known migrations and technological innovations" the phylogeny of the Y chromosome contains several independent bursts or rapid expansions of male numbers and these authors suggest this is because "privileged male lineages could undergo preferential amplification for generations".  In a similar manner, Balaresque et al. (2015) observed that in Asian pastoral nomads Y-chromosome descent clusters may be associated with a greater ease of transmission of human Y-chromosomes through time and space as a result of gaining the skill to use horses for transport.  

It seems to me that an analogous burst of Y-chromosome mutations downstream of I-L233 happened during the Iron Age when Germanic tribes migrated out of Scandinavia concurrent with their development of an iron-riveted, clinker-built ship technology that facilitated swift movement on water over very considerable distances.  As a result, rivers, lakes, coastal voyages and even passage across open sea created well established routes by which their Y haplogroups became distributed throughout Europe.  Of special significance were the trans North Sea  routes that linked the British Isles and Scandinavia.

In addition it is worth noting that these demographic movements involved pagan tribal groups typified by the Anglo Saxons and Vikings who had a warrior, "raiding and trading" culture that radiated from communities bordering the Baltic sea.  In these groups social hierarchy tended to foster powerful male elites that practiced both polygamy and concubinage. It seems reasonable to think that these practices would further favour the proliferation and accelerated mutation of their Y-DNA.  Hence it may not be too surprising that we find so many Baltic clades within I-Y4252. 

Woolf (2015) suggests, based on archaeological evidence, that the development of the iron-rivet, clinker built ship technology was centered in Scania (southern Sweden) and Denmark.  The earliest surviving example of a Germanic vessel using the clinker technique comes from Nydam Moss, an archaeological site on the eastern side of the Danish peninsula just north of the modern border with Germany.  It dates from 320-350AD.   At Vendal and Valsgarde in the Swedish province of Uppland and in England at Sutton Hoo and Snape in Suffolk and at Sarre in Kent, sixth and seventh century ship burials have been excavated.  Those examples from Suffolk and Kent provide confirmation that the English "Saxon Shore" had extensive interactions with Scandinavia from 500-600AD (Brookes, 2007).  In this connection the ship burials at Gunnerstad, Gamleby, Tjust, Sweden, are worth mentioning as all four Swedish men derived for I-Y33765 have genealogy linking them to the surrounding area.

Figure 3: Proportions of major coin types from the 8th to 12th century found in countries bordering the Baltic Sea.  This illustration is based on data from Table 1, page 9, Talvio (2002).

Further archaeological evidence for contacts between England and the lands of the Baltic and Nordic regions is provided by coin finds (Talvio, 2002).  Interestingly, by comparing Figures 2 and 3, you will see that the proportion of English coins found in countries surrounding the Baltic Sea is higher in those areas where the Baltic clades observed downstream of I-Y4252 have also been recorded.  This would seem to support the idea that these areas had more contact with England during the Dark  Ages.  In 2008, a hoard of coins was found at Hellero, Vastra Ed, Tjust (Palm,2008).  This Swedish archaeological site is again close to the area where all four I-Y33765 Swedish men have documented direct-line male ancestry.  All the English coins in that hoard were made by mints operating in southern England at the end of the first millenium; in other words, in a similar area to where men on the English arm of I-Y33765 have their medieval ancestry.  

So, based on archaeological evidence, Viking Age contact can be substantiated that would inevitably introduce Y-DNA haplotypes from the Baltic region into England. The Baltic clades that proliferated downstream of I-Y4252  are examples of this process.     

 References

Balaresque, P. et al. (2015) Y-chromosome descent clusters and male differential reproductive success: Young lineage expansions dominate Asian pastoral nomadic populations. European Journal of Human Genetics 23, 1413-1422

Brookes, S. (2007) Boat-rivets in Graves in pre-Viking Kent: Reassessing Anglo-Saxon Boat-burial Traditions. Medieval Archaeology 51, 1-18

Cullen, B. (2020) Comment made in activity feed of I2a Project, FTDNA

Palm, V.,Nilsson, N.,Jonsson, K. (2008) Hellero - ytterligare en silverskatt fran Tjust, Smaland. Mynstudier, November 17-33

Poznik, G.D. et al.  (2016) Punctuated bursts in human male demography inferred from 1244 worldwide Y-chromosome sequences. Nat. Genet. 48(6), 593-599

Talvio, T (2002) Coins and coin finds in Finland AD 800-1200, Ed. Torsten Edgren, ISKOS, Finland.

Woolf, A. (2015) Sutton Hoo and Sweden Revisited In: The Long Seventh Century, Continuity and discontinuity in an age of transition. Ed.G.Alessandro. Peter Lang AG.